Wednesday, April 23, 2014

Everything but Bench Snow

Yesterday's Intermountain cold front delivered in spades.

Wind
Lower-elevation wind gusts of 78 mph in Eureka, 74 in Sherwood Hills, 74 at Diddle Knoll, 73 at Fish Springs, 73 in Lehi, 72 in Tremonton, 72 in Draper, 72 in Wendover (I-80 Milepost 1), and 71 near Magna. The 72 in Tremonton toppled a couple of semis and occurred just ahead of the cold front.

Source: MesoWest

The 74 at Diddle Knoll in the West Desert occurred just after frontal passage, although this site had gusts to 70+ both ahead of and following frontal passage.

Source: MesoWest. Note data outage overnight.

I haven't heard of any reports of semis blown over on I-80. This event, however, never reached the magnitude of the 25 March 2006 event that featured post frontal wind gusts of just over 80 mph.

Dust
The previous post illustrates the plume that extended from the Sevier Dry Lake Bed over the Salt Lake Valley. Online data from the Utah Division of Air Quality shows a remarkable spike in PM2.5 concentrations to almost 150 ug/m3, very near the time of frontal passage. If that value is legit, it is much higher than anything observed during inversion events the past two winters in the Salt Lake Valley.

People have tried to argue that these dust storms are "natural" events, but they aren't. The strong winds are natural, but dust emissions from the Sevier Dry Lake Bed and other sources clearly have a strong anthropogenic component. Diversions from the Sevier River limit water flow to the lake bed and human disturbance of the land surface is a major factor in dust emissions.

Unfortunately, the deposition of dust onto the mountain snowpack will likely screw up the corn skiing later this spring. Whether or not we see a chocolate-brown snowpack emerge with the spring melt as we did after the 2002 Tax Day Storm remains to be seen, but I won't be surprised if we do.

Snow
For now, that dust is buried under and probably a bit within the mountain snow that fell overnight. Looks like 4 inches at Alta-Collins, get them back over the 100 inch snow depth again. Unfortunately, precipitation did not hang on until the later hours of the night when it would have been cold enough to perhaps get a skiff of snow down to bench level. Instead, accumulating snow only made it down to about the upper reaches of Olympus Cove. You can't have everything!

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The Wasatch Weather Weenies discuss the weather and climate of the Wasatch Front and Mountains, western United States, and beyond.

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